Krishnakanth Rapaka

Scalable Video Coding Extension for HEVC

This paper describes a scalable video codec that was submitted as a response to the joint call for proposals issued by ISO/IEC MPEG and ITU-T VCEG on HEVC scalable extension. The proposed codec uses a multi-loop decoding structure. Several inter-layer texture prediction methods are employed to remove the inter-layer redundancy. Inter-layer prediction is also used when coding enhancement layer syntax elements such as motion parameter and intra prediction mode, to further reduce bit overhead. Additionally, alternative transforms as well as adaptive coefficients scanning are used to code the prediction residues more efficiently. Experimental results are presented to demonstrate the effectiveness of the proposed scheme. When compared to HEVC single-layer coding, the additional rate overhead for the proposed scalable extension is 1.2% to 6.4% to achieve two layers of SNR and spatial scalability.

Generalized inter-layer residual prediction for scalable extension of HEVC

Scalable video coding extension of HEVC (SHVC) is being developed by Joint Collaborative Team on Video Coding (JCT-VC) of ISO/IEC MPEG and ITU-T VCEG. Different from scalable video coding extension of H.264/AVC (SVC), SHVC employs a multi-loop decoding framework so that the inter-layer residual prediction in SVC does not perform well in SHVC. In this paper, a method called generalized inter-layer residual prediction (GILRP) is proposed. To improve prediction accuracy, the residual predictor is derived with the information from both base and enhancement layers. Moreover, three additional weighting types are introduced on top of inter coding modes to further compensate errors caused by base layer quantization. Simulations under SHVC common test conditions defined by JCT-VC show that 2.9%, 5.1% and 4.9% overall luma BD-rate reduction on average were obtained over SHVC reference software for configurations of random access, low delay with P slices, and low delay with B slices, respectively.

Intra Block Copy in HEVC Screen Content Coding Extensions

With the emerging applications such as online gaming and Wi-Fi display, screen content video, including computer generated text, graphics and animations, becomes more popular than ever. Traditional video coding technologies typically were developed based on models that fit into natural, camera-captured video. The distinct characteristics exhibited between these two types of contents necessitate the exploration of coding efficiency improvement given that new tools can be developed specially for screen content video. The HEVC Screen Content Coding Extensions (HEVC SCC) have been developed to incorporate such new coding tools in order to achieve better compression efficiency. In this paper, intra block copy (IBC, or intra picture block compensation), also named current picture referencing (CPR) in HEVC SCC, is introduced and discussed. This tool is very efficient for coding of screen content video in that repeated patterns in text and graphics rich content occur frequently within the same picture. Having a previously reconstructed block with equal or similar pattern as a predictor can effectively reduce the prediction error and therefore improve coding efficiency. Simulation results show that up to 50% BD rate reduction in all intra coding can be achieved with intra block copy enabled, compared to the HEVC reference encoder without this tool. Significant BD rate reductions for other coding configurations are also observed.

High Frequency SAO for scalable extension of HEVC

Scalable extension of HEVC, a.k.a. SHVC, is being standardized by the Joint Collaborative Team on Video Coding (JCT-VC). SHVC employs one of the most important coding tools called interlayer prediction, in which. Reconstructed base layer pictures can be used as reference pictures to predict enhancement layer pictures. Therefore, how to efficiently generate interlayer reference pictures to improve coding efficiency is one of the core research topics for the new international standard. In this paper, we presented High Frequency SAO filter (HF-SAO), which extends Sample Adaptive Offset filter (SAO) in HEVC to SHVC. Experimental results based on SHVC reference software version 1.0 show that HFSAO achieves 1.2% (Luma), 1.4% (Cb), 1.4% (Cr) average BD-rate reduction for the enhancement layer coding, which makes itself one of the most promising candidate interlayer filters to the new generation of scalable video coding standard.